1. Field of the Invention
The present invention relates to optical fiber ribbons for optical fiber telecommunications cables. More particularly, the present invention relates to a stackable optical fiber ribbon design that provides access to one or more of the optical fibers incorporated without the use of special tools or techniques.
2. Description of the Prior Art
Optical fiber cables are now widely used in the telecommunications field to transmit information. Optical fiber cables manufacturers are frequently relying on optical fiber ribbons or multi-ribbons for high fiber count cables because they provide an organized structure which increases packing efficiency and permits rapid splicing and connectorization. Optical fiber ribbons generally comprise a plurality of optical fibers arranged in a planar array and coated with a matrix material which holds the fibers together in the planar array. Each of the optical fibers generally comprises a core, cladding, primary and secondary coatings formed from a ultraviolet light (UV) curable material and an outer color layer. In some fibers, the secondary coating contains color pigments and the outer color layer is omitted. Each of the fibers in the ribbon is given a different color so that each may be identified and distinguished from the other fibers in the ribbon.
From time to time, it is desirable to access one or more of the optical fibers in a ribbon for the purposes of splicing. Access to the optical fibers in a ribbon is generally more difficult than access to fibers loosely held in a cable because the ribbon matrix material must be removed before accessing the fibers. The removal of the ribbon matrix material must be done carefully so as not to cause damage to the delicate optical fibers. Generally, the prior art has used release agents between the optical fibers and the ribbon matrix material so that the matrix material does not adhere strongly to the optical fiber ribbons.
In the past, access to optical fibers in an optical fiber ribbon has required the use of tools and chemicals. For example, U.S. Pat. No. 5,643,393 discloses a method for accessing individual fibers in an optical fiber ribbon by securing an adhesive tape, having glue on its backing, to a substrate surface. The ribbon matrix is placed on the glue and after the glue has set, the optical fiber ribbon is pulled away from the tape to break the matrix material and delaminate one surface thereof.
U.S. Pat. No. 5,460,683 also discloses a similar method wherein a strip of adhesive tape having a plastic card element attached to one end is placed on a support surface with an adhesive surface of the strip faces upwardly. A selected span of optical fiber ribbon is placed across the exposed top surface of the tape and across the plastic card element. Glue is positioned beneath the span length of the optical fiber ribbon overlaying the plastic card element so as to bond the ribbon to a portion thereof. The end of the optical fibber ribbon overlaying the plastic card element is lifted to initiate delamination of the matrix material.
It has been found that the techniques described above can be messy and unreliable for removing the matrix material from the ribbon. Such techniques can also put too much tension on the fibers and cause damage thereto. It is desirable to have an optical fiber ribbon which does not require such methods to separate the optical fiber ribbon matrix material from the optical fibers encapsulated thereby.